Re: [Patch V5 2/3] tpm_tis-spi: Support hardware wait polling

Mark Brown
2023-03-01T12:37:39Z

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On Wed, Mar 01, 2023 at 08:27:45AM -0400, Jason Gunthorpe wrote:
> On Wed, Mar 01, 2023 at 11:56:53AM +0000, Krishna Yarlagadda wrote:

> > TPM device connected behind half duplex controller can only work
> > this way. So, no additional flag needed to check.

> Just because a DT hooks it up this way doesn't mean the kernel driver
> can support it, eg support hasn't been implemented in an older SPI
> driver or something.

> If the failure mode is anything other than the TPM doesn't probe we
> will need to check for support.

It's not like these buses are hot pluggable - someone would have to
design and manufacture a board which doesn't work. It's probably
reasonable for this to fail with the SPI subsystem saying it can't
support things when the operation is tried.

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